At the risk of being a customer speaking about an area only the developers can truly know about, after being unable to log on my main character for many hours today, and as someone with 40 years' experience in data center server storage and network R&D:

It appears that a device in the network between the game server and my client is detecting a routine zone full message, which the client would normally retry in a matter of seconds without the player even knowing this occurred, and blocking some part of any further communication between my client and the server. But only for a specific character.

So it appears that some "firewall" which is part of the DDOS recovery process is learning from character logon failures and blocking subsequent packets related to that character logging on. This "firewall" could be located in the network part of the Data Center where Mateus is, or could be located at a DDOS vendor.

The following is written in a style which would be offensive to a US company, but is the style I have been trained to use when working with a valued partner company in Japan from whom we were purchasing a product over the course of a many year relationship:

It is incorrect that the "zone full" message results in long term inability to log on a particular character in this way. This bad customer experience is not necessary. The function which learns and blocks subsequent logons needs to be corrected, to eliminate this bad player experience.

World of Warcraft does not behave this way under DDoS
Guild Wars 2 does not behave this way under DDoS
Wildstar did not behave this way under DDoS
Blade and Soul does not behave this way under DDoS
EverQuest II does not behave this way under DDoS
Warhammer did not behave this way under DDoS

This is my first post, ever, on the Square Enix forums.